It is often desirable to illuminate fish tanks and the like with lights of different color. However, it had been found that using more than one color at a time results not in a visually pleasing effect, but rather in a muddied or murky color that is not pleasing. Accordingly, it is desirable to provide light of a single color to fish tanks. It is also desirable to provide a device in which it is possible to alter the color of the illuminating light, thereby to change the visual effect in the fish tank. Rapid changing of the colors is to be avoided for this adversely effects the spawning cycle of fish in the tank.
Prior art devices known to the inventor which provide light of different colors to fish tanks suffer from extreme unwanted reflection and refraction of light having the different colors thereby creating a muddy or murky effect in the fish tank. The device of the present invention is designed to reduce to a minimum all unwanted reflection and refraction, thereby to produce a relatively pure single color effect in the fish tank.